When I got the 1st Gen RT, I opted for the Type Cover. Why? Because I know that I was going to be typing a lot and I wanted the best possible option, which is what the Type cover offered. The only place that I have used the Touch cover is in stores and the little time that I have had to spend with it suggested to me that while the technology - or what the MS folks have done with it - is amazing, it requires a bit of effort, which involves time, which I did not want to spend given that an easier option did (and does exist). Having said that, there was a brief period of time when I was seriously considering the Touch cover but only to use as a cover and when folded back. But once I gained a bit of confidence in the Type cover, I quickly gave up the idea.
Recently, I bought the Type Cover 2. I did this because (1) of the backlighting and (2) because of the colour (I got the purple one) and (3) because I read that the MS design people had made some changes in terms of key travel and the sound level. I have not been disappointed.
And, having just bought the Surface 2, I have come to appreciate the Type cover 2 even more as I can now use some of the added gestures etc.